FIG. 1 is a block diagram of a conventional panel driving circuit. The conventional panel driving circuit 100 includes a graphic memory 120 and an OSD (On Screen Display) memory 130. The graphic memory 120 corresponds to one frame size. Background data DI and OSD data OSD_DATA, that correspond to an image to be displayed on a panel 150, are output from a microprocessor interface 110 and stored in the graphic memory 120 and the OSD memory 130.
The graphic memory 120 and the OSD memory 130 transmit the background data SDOUT_PRE and OSD data OSD_DATA to an alpha-blending circuit 140. The alpha-blending circuit 140 blends the background data SDOUT_PRE and OSD data OSD_DATA with each other in a specific ratio and transmits the blended data SDOUT to the panel 150.
FIG. 2 is a block diagram of a conventional panel driving circuit that simultaneously receives a moving image and a still image and displays them. The panel driving circuit 200 receives moving image data MD via a moving image interface 210 and still image data SD via a microprocessor interface 220, which are then sent to a MUX 230.
The MUX 230 selects one of the moving image data MD and the still image data SD under the control of a controller 280, and the selected data is stored in a memory 240. A source driver 250 and a gate driver 260 transmit the moving image data MD or still image data SD stored in the memory 240 to a panel 270. The still image data SD is typically not transmitted to the panel 270 if the moving image MD is transmitted to the panel 270.
FIG. 3 is a timing diagram illustrating the operation of the panel driving circuit of FIG. 2. Referring to FIG. 3, a vertical synchronization signal VSYNC is activated once for each frame. Dot CLOCK is a reference clock signal. The moving image data MD typically cannot be transmitted to the panel 270 while the still image data SD is being displayed by the panel 270. That is, after a first frame 1F of the moving image data MD is sent to the panel 270(i), second, third and fourth frames 2F, 3F and 4F of the moving image data MD typically cannot be transmitted because the still image data SD is transmitted to the panel 270(ii).
As described above, the conventional panel driving circuit, typically, cannot transmit the moving image data and still image data to the panel simultaneously. Furthermore, the circuit should store the moving image data in the memory thereby increasing current consumption.